A face image recognition technique is utilized in security systems, ATM (Automated Teller Machine) withdrawing systems, etc. A representative face image recognition system may be a face recognition system using a single camera. When a criminal or a person with a fraudulent intention inputs a disguised photo image through a camera with a purpose, the face recognition system has suffered from a difficulty in discriminating whether a face in the photo image is a disguised face or a genuine face.
In order to solve this problem, there has been proposed a method to discriminate a disguised face and a genuine face by detecting whether a face has an irregularity using a three-dimensional distance sensor or two cameras. However, the method using the three-dimensional distance sensor is relative expensive and has a disadvantage that it does not operate under natural light in an external environment. Meanwhile, the method using two cameras has a difficult to install the cameras in existing equipments and does not exhibit a satisfactory performance. Besides, the technique to discriminate whether a face is a photo image using the single camera uses a method to locate a border around a photo to verify the photo image. However, this technique has a limitation that does not verify a photo image which is cut in compliance with a face shape. In addition, it is difficult to discriminate a disguised face with a mask that is similar to and puts on a face or with a disguised silicon skip.